1. Field of the Invention
The present invention relates to a power-saving control circuitry and a control method. More particularly, the present invention relates to a power-saving control circuitry of an electronic device and the controlling method thereof.
2. Description of the Related Art
FIG. 1 is a schematic block diagram showing the power control circuitry of a conventional electronic device (for example, an integrated circuit or an application specific integrated circuit). As shown in FIG. 1, the electronic device has a power control circuit 101. The power control circuit 101 receives a digital clock signal DCLK to control a clock pulse generator circuit 103. The clock pulse generator circuit 103 generates a plurality of clock signals CLK1, CLK2, CLK3 and CLK4, which are sent to various principal integrated circuit chips (for example, digital circuits) 105, 107, 109 and 111. When the electronic device enters into an power-saving mode (such as a stand-by or a sleep mode), the power control circuit 101 controls the clock pulse generator circuit 103 to stop sending clock signals CLK1, CLK2, CLK3, CLK4 so that power to the IC chips are temporarily shut down to save power.
Yet, the conventional power control circuit has few drawbacks. When the electronic device enters into a stand-by or a sleep mode, power to the IC chips can only be cut by stopping all the clock signals going to the IC chips. Furthermore, power to the power control circuit 101 has to be maintained because the power control circuit 101 still has to receive external signals and the digital clock signal DCLK cannot be stopped for just one moment. Hence, any further reduction of current is prevented.
In addition, most conventional electronic devices have additional memory units to assist the operation of various IC chips aside from the normal circuits (digital or analogue). However, only static random access memory has an automatic power shutdown design to cut off power all by itself. Other types of memories comprising the flash ROM has no self-switching design so that these devices must be turned on or off with the help of an external control circuit. Therefore, unlike the IC chips that can be controlled by the clock signal circuits as shown in FIG. 1, a special circuit must be set inside the power control circuitry for controlling the memory units. In other words, complicated circuit design has to be introduced and the production cost bound to be higher.